Improving the quality of stabilization pond effluents using hybrid constructed wetlands

Nitrate and ammonium removal in constructed wetlands: Experimental insights and zero-dimensional numerical modeling

Constructed wetlands (CWs) have emerged as effective wastewater treatment systems, mimicked natural wetland processes but engineered for enhanced pollutant removal efficiency. Ammonium (NH4+) and nitrate (NO3-) are among common pollutants in wastewater, posing significant environmental and health risks. The primary objective of this study is to compares the performance of CWs using gravel and three sizes of natural pumice, along with phragmites australis, in horizontal and horizontal-vertical CWs for nitrate and ammonium removal in the complementary treatment of domestic wastewater. Additionally, the study aims to develop and validate a numerical model using MATLAB software to predict the removal efficiency of these pollutants, thereby contributing to the optimization of CW design and operation. The model operates as a zero-dimensional model based on the law of mass conservation, treating the wetland as a completely mixed reactor, thus avoiding complexities associated with solute movement in porous media. It accurately could predict removal efficiency of chemical, biochemical, and biological indicators while considering active and passive absorption mechanisms by plant uptake. Notably, the determination of coefficients in the model equation does not rely on potentially error-prone laboratory measurements due to sampling issues. Instead, optimization techniques alongside field data robustly estimate these coefficients, ensuring reliability and practicality. Results indicate that higher pollutant concentrations increase reaction rates, particularly enhancing CW efficiency in ammonium removal. Pumice, especially in larger sizes, exhibits superior absorption due to increased porosity and surface area. Overall, the model accurately predicts nitrates concentrations, demonstrating its potential for CW performance optimization and confirming the significance of effective pollutant removal strategies in wastewater treatment.

A bibliometric analysis of green technologies applied to water and wastewater treatment

Freshwater scarcity, a problem that has arisen particularly as a result of the progressive environmental damage caused by human consumption patterns, is strongly associated with a loss of living quality and a drop in global socioeconomic development. Wastewater treatment is one of the measures being taken to mitigate the current situation. However, the majority of existing treatments employ chemicals that have harmful environmental consequences and low effectiveness and are prohibitively expensive in most countries. Therefore, to increase water supplies, more advanced and cost-effective water treatment technologies are required to be developed for desalination and water reuse purposes. Green technologies have been highlighted as a long-term strategy for conserving natural resources, reducing negative environmental repercussions, and boosting social and economic growth. Thus, a bibliometric technique was applied in this study to identifying prominent green technologies utilised in water and wastewater treatment by analysing scientific publications considering authors, keywords, and countries. To do this, the VOSviewer software and Bibliometrix R Package software were employed. The results of this study revealed that constructed wetlands and photocatalysis are two technologies that have been considered as green technologies applicable to the improvement of water and wastewater treatment processes in most scientific articles.

Characterization of Volcano-Sedimentary Rocks and Related Scraps for Design of Sustainable Materials

This work started as a joint academia and company research project with the aim of finding new applications for domestically sourced volcanic products and related waste (pumice, lapillus, zeolitic tuff and volcanic debris from Tessennano and Arlena quarry) by creating a database of secondary volcanic raw materials and their intrinsic characteristics to help industry replace virgin materials and enhance circularity. In this context, accurate chemical, mineralogical, morphological, granulometric and thermal characterizations were performed. Based on the results presented, it can be concluded that due to their lightness, these materials can be used in the design and preparation of lightweight aggregates for agronomic purposes or in the construction field. Furthermore, due to their aluminosilicate nature and amorphous fraction, pumice and lapillus can play the role of precursor or activator for geopolymer preparation. With its porous nature, zeolitic tuff can be exploited for flue gas treatment. Due to the presence of feldspathic phase (sanidine), these materials can be used in tile production as a fluxing component, and with their pozzolanic activity and calcium content, they have application in the binder field as supplementary cementitious material or as aggregates.